Campaign contributions from oil industry executives to Sen. John McCain rose dramatically in the last half of June, after the senator from Arizona made a high-profile split with environmentalists and reversed his opposition to the federal ban on offshore drilling.

Oil and gas industry executives and employees donated $1.1 million to McCain last month -- three-quarters of which came after his June 16 speech calling for an end to the ban -- compared with $116,000 in March, $283,000 in April and $208,000 in May.

McCain said the policy reversal came as a response to rising voter anger over soaring energy prices. At the time, about three-quarters of voters responding to a Washington Post-ABC News poll said prices at the pump were causing them financial hardship, the highest in surveys this decade.

Opening vast stretches of the country's coastline to oil exploration would help America eliminate its dependence on foreign oil, McCain said.

"We have untapped oil reserves of at least 21 billion barrels in the United States. But a broad federal moratorium stands in the way of energy exploration and production," he said. "It is time for the federal government to lift these restrictions."

McCain delivered the speech before heading to Texas for a series of fundraisers with energy industry executives, and the day after the speech he raised $1.3 million at a private luncheon and reception at the San Antonio Country Club, according to local news accounts.

"The timing was significant," said David Donnelly, the national campaigns director of the Public Campaign Action Fund, a nonpartisan campaign finance reform group that conducted the analysis of McCain's oil industry contributions. "This is a case study of how a candidate can change a policy position in the interest of raising money."

Brian Rogers, a McCain campaign spokesman, said he considers any suggestion that McCain weighed fundraising into his calculation on drilling policy "completely absurd." Rogers noted that oil and gas money in June still accounted for a very small fraction of the $48 million raised by the campaign and by the Republican National Committee through its Victory Fund.

"John McCain takes positions because he thinks it's the right thing to do for America," Rogers said. "He has a long track record of doing that. And he's often made decisions that hurt with his fundraising base."

Oil and gas executives have not traditionally been a major source of campaign money for McCain. A breakdown of giving by the Center for Responsive Politics shows the industry falls 12th on a list of top donors, well behind securities firms, lawyers, banks, and real estate and health professionals.

McCain has historically sided against a number of the industry's interests, opposing efforts to open certain public lands to drilling and embracing proposals aimed at tackling global warming well before oil executives were ready to do so.

Patrick C. Oxford, chairman of the Texas-based law firm Bracewell & Giuliani, said there has been a contrast between the way the industry embraced George W. Bush, a favorite son, and McCain. Oxford said that until recently oil industry officials were motivated to back McCain because of talk by Sen. Barack Obama "about needing to tax the hell out of the oil companies."

That started changing in mid-June, he said. McCain's speech and subsequent visit to Texas served the purpose of reintroducing him to the oil industry. Oxford, whose law firm represents several large oil companies, wrote his first check to McCain on June 27.

Charting the political donations of oil executives may be the best way to evaluate the industry's level of interest in a presidential candidate, said Robin West, chairman of PFC Energy, an industry adviser. Unlike other businesses, oil and gas companies do not have a large labor force that can provide a candidate an army of volunteers. And oil and gas concerns are geographically confined, largely in states that are not viewed as central to a presidential election strategy.

"It's for those reasons that the oil industry has always tried to be a substantial contributor," West said.

And West said he thinks McCain gave energy executives what they needed to get more solidly in his corner -- a pledge to reverse a federal policy that has frustrated the industry for years.

"I think people thought it was a sensible thing that was long due," West said. "I think the industry was very appreciative."